How a Revolutionary Genetic Discovery Is Changing What We Know About Anorexia

“It’s not just picking up the spoon and putting food in their mouth.”

Nattakorn Maneerat/iStock/Getty

“Why won’t she eat more? Why won’t he eat more?”

Cynthia Bulik, a clinical psychologist, and founding director of the University of North Carolina at Chapel Hill’s Center of Excellence for Eating Disorders, says this is the question she hears repeatedly from parents of children with anorexia nervosa, an eating disorder which causes an intense fear of gaining weight or becoming fat, even when underweight. “And we’re saying it’s not that simple,” she adds. “It’s not just picking up the spoon and putting food in their mouth.”

It’s estimated that 30 million Americans have an eating disorder at some point in their lives, which includes anorexia, bulimia nervosa, and binge eating disorder. On Monday, the scientific journal Nature Genetics published a study exploring the genetics specifically of anorexia, by Bulik and a team of researchers from all over the world. Twin studies conducted over the last decade, in which identical or fraternal twins are subjects, have shown that eating disorders are heritable. But twin studies can’t reveal what precise genes are involved nor what they do. In recent years, Bulik explains, there’s been a “revolution in genetic technology,” allowing researchers to compare the entire genome of people with an illness to the entire genome of people without that illness.

That’s precisely what the new study did. It compared the genetics of nearly 17,000 people with anorexia to the genetics of over 55,000 people without anorexia, from 17 countries. The study identified regions on the genome, or loci, that differed significantly in people with anorexia versus people without the illness, which provides a major biological insight into the nature of the illness and its treatment. Bulik suggests that scientists will eventually be able to use novel medications that are “directed toward the underlying biology of the illness,” findings that she describes as “both a breakthrough and a first step.”

“Professor Cynthia Bulik and her colleagues’ work is truly ground-breaking,” said Jacinta Tan, Consultant Child and Adolescent Psychiatrist at Aneurin Bevan University Health Board in Wales. “That’s because it is a game changer in shifting our understanding of eating disorders.”

The results led the researchers to conclude that anorexia, which had previously been considered to be a psychiatric disorder with physical aspects, now should be rebranded as a “metabo-psychiatric disorder” to emphasize the illness’ metabolic component.They found positive genetic correlations with obsessive compulsive disorder (OCD), depression, and anxiety. 

Often people with anorexia engage in intense physical activity and exercise. Previously, this was thought to be just another manifestation of the psychological desire to burn calories and lose more weight. “We know that patients with anorexia are often hyperactive, even at really low weights. They will be pacing around their hospital room,” Bulik explains. “We have always psychologized that.” But the study revealed a positive genetic correlation with physical activity, which means that people with anorexia are more likely than people without the illness to have the genetics for increased physical activity. There might, in fact, be a genetic reason for their high physical activity.

Physicians have “often blamed patients for being so active,” Bulik says, but she hopes the research will allow health professionals to look at behaviors associated with anorexia in a “less patient-blaming way.” Her goal? “We need to get into the medical school curricula and the curricula of all the health professionals to completely change how they think about this illness.”

When it comes to any illness, health care providers want to minimize the amount of time the patient spends suffering with the symptoms. For people with anorexia, however, the stakes are often higher: the body starts using itself for fuel when food intake is restricted. As people become more and more emaciated, they can experience issues with organ systems in the body. “The amount of physical damage increases astronomically the longer you have the illness,” Bulik told me.

That’s not even the full picture of complications from this illness though: anorexia nervosa has the highest mortality rate of any non-substance abuse psychiatric disorder. A previous study found lifetime prevalence of anorexia in the US was three times higher among females (0.9 percent) than males (0.3 percent). But nonetheless, an estimated 10 million American men will have an eating disorder at some point in their lives. Although recovery is always possible, the likelihood of someone recovering from anorexia decreases the longer the illness remains untreated.

Bulik prefers the word “crystallized” to describe the process of how anorexia becomes entrenched in a patient’s approach to life. “And whenever something is crystallized,” she says, “it’s harder to change than when it’s more fluid in the early stages.” Anorexia is a “perplexing illness” for both health care professionals and patients’ family and friends, for whom eating is just natural. And while people with other psychiatric disorders like depression might come to doctors and ask for help, people with anorexia are often reluctant to seek treatment because the rigorous control of food intake makes them feel better in the short term. 

The new findings about the biological underpinnings of anorexia further bolster the point she shares with people in recovery. Bulik tells people recovering from anorexia that this is “an uphill battle against your biology, but it’s one you have to fight.” She adds, “Because the alternative, unfortunately, can be death.”


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